
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <windows.h>
#include <iostream>
#include <linmath.h>
#include <matrix.h>

// ASCII 字符总共只有0到127，一共128种字符
#define MAX_CHAR 128

static const struct
{
    float x, y;
    float r, g, b;
} vertices[3] = {
    { -0.6f, -0.4f, 1.f, 0.f, 0.f },
    { 0.6f, -0.4f, 0.f, 1.f, 0.f },
    { 0.f, 0.6f, 0.f, 0.f, 1.f }
};

static const char* vertex_shader_text = R"(
    #version 110
    uniform mat4 MVP;
    attribute vec3 vCol;
    attribute vec2 vPos;
    varying vec3 color;
    void main() {
        gl_Position = MVP * vec4(vPos, 0.0, 1.0);
        color = vCol;
    }
)";

static const char* fragment_shader_text = R"(
    #version 110
    varying vec3 color;
    void main() {
        gl_FragColor = vec4(color, 1.0);
    }
)";

static void error_callback(int error, const char* description)
{
    fprintf(stderr, "Error: %s\n", description);
}

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GLFW_TRUE);
}

static void drawString(const char* str) {
    static int isFirstCall = 1;
    static GLuint lists;

    // 如果是第一次调用，执行初始化
    if (isFirstCall) {
        // 为每一个ASCII字符产生一个显示列表
        isFirstCall = 0;

        // 申请MAX_CHAR个连续的显示列表编号
        lists = glGenLists(MAX_CHAR);

        // 把每个字符的绘制命令都装到对应的显示列表中
        wglUseFontBitmaps(wglGetCurrentDC(), 0, MAX_CHAR, lists);
    }

    // 调用每个字符对应的显示列表，绘制每个字符
    for (; *str != '\0'; ++str)
    glCallList(lists + *str);
}

int main() {
    GLFWwindow* window;
    double time = glfwGetTime();
    GLuint vertex_buffer, vertex_shader, fragment_shader, program;
    GLint mvp_location, vpos_location, vcol_location;

    glfwSetErrorCallback(error_callback);

    if (!glfwInit())
        exit(EXIT_FAILURE);

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

    window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glfwSetKeyCallback(window, key_callback);

    glfwMakeContextCurrent(window);
    gladLoadGL();
    glfwSwapInterval(1);

    // NOTE: OpenGL error checks have been omitted for brevity

    glGenBuffers(1, &vertex_buffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
    glCompileShader(vertex_shader);

    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
    glCompileShader(fragment_shader);

    program = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);

    mvp_location = glGetUniformLocation(program, "MVP");
    vpos_location = glGetAttribLocation(program, "vPos");
    vcol_location = glGetAttribLocation(program, "vCol");

    glEnableVertexAttribArray(vpos_location);
    glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
                          sizeof(vertices[0]), (void*) 0);
    glEnableVertexAttribArray(vcol_location);
    glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE,
                          sizeof(vertices[0]), (void*) (sizeof(float) * 2));

    while (!glfwWindowShouldClose(window))
    {
        float ratio;
        int width, height;
        mat4x4 m, p, mvp;

        glfwGetFramebufferSize(window, &width, &height);
        ratio = width / (float) height;

        glViewport(0, 0, width, height);
        glClear(GL_COLOR_BUFFER_BIT);

        mat4x4_identity(m);
        mat4x4_rotate_Z(m, m, (float) glfwGetTime());
        mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
        mat4x4_mul(mvp, p, m);

        glUseProgram(program);
        glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwDestroyWindow(window);

    glfwTerminate();
    exit(EXIT_SUCCESS);
}
/*
# 查询当前使用的镜像源
yarn config get registry

# 设置为淘宝镜像源
yarn config set registry https://registry.npmmirror.com/

# 还原为官方镜像源
yarn config set registry https://registry.yarnpkg.com/
*/